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Curing & stabilization of cement-asbestos products: this article describes how asbestos cement roofing, siding, pipe, and other products were cured after the wet manufacturing process. Curing methods for asbestos-cement varied from autoclave, air-drying, to storage under-water!
Cement asbestos materials: this article series describes asbestos cement products & materials and the history of their production and use. This article includes text & data Adapted from Rosato (1959 out of print) on the production and use of asbestos-containing materials, adding photographs, inspection, repair and maintenance advice, and updates on asbestos hazards involved in the installation, repair, or demolition of asbestos cement products such as roofing and siding or asbestos millboard that remain in place on buildings.
Our page top photograph shows badly broken cement asbestos roofing shingles on a building in upstate New York.
Three basic processes are available for
curing the asbestos-cement products. These are similar to
the procedures used for ordinary concrete materials,
however, they are usually maintained under better actual
control. The oldest procedure is wet curing.
The products are
allowed to age in a warm humid atmosphere from 21 to 28
[Click to enlarge any image]
Pipe products, under this system, are frequently stored
under water after approximately 7 days of curing in air.
Typically, with cement products, the strength of
asbestos-cement products increases as time passes. This condition is
particularly true in the first year.
Occasionally, the products are cured for approximately a day in moist steam at atmospheric pressure. The average
curing temperature is approximately 85 °C. The
tempera-ture-time cycle varies and depends upon the product.
Atmospheric steam curing is essentially an acceleration of
normal curing; it cures products without requiring a long
Figure 3.3. Asbestos-cement product being cured in autoclave.
(Courtesy Johns-Manville Corp.)
Autoclave curing is more popular. See Figure 31. It uses
saturated steam at pressures between 100 and 250 psi. This
process is not simply an accelerated cure, giving an
ade-quately cured product in one day, but it also alters the
character of the material.
The Italian inventor, Dr.
Morbelli, started the process of substituting finely ground, pure
silica flour for a portion of the cement in the mixture.
silica flour and the cement react under the curing conditions
to form a crystalline product in place of the typical cement
This method takes into consideration the chemical
reac-tion between calcium hydroxide and silica which forms a
hydrated calcium silicate. The silica is added to the
com-position of the product to react with the calcium hydroxide
which is formed when the cement reacts with water. Steam
cure under pressure provides for the chemical reaction.
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 Asbestos, its Industrial Applications, D.V. Roasato, engineering consultant, Newton MA, Reinhold Publishing Co., NY, 1959, Library of Congress Catalog No. 59-12535. We are in process of re-publishing this interesting text. Excerpts & adaptations are found in InspectApedia.com articles on asbestos history, production & visual identification in and on buildings.
 "Asbestos in Plastic Compositions", A.B. Cummins, Modern Plastics [un-dated, pre 1952]
 "Asbestos in Your Home," Spokane County Air Pollution Control Authority, Spokane WA 509-477-4727 www.scapa.org provides a one-page image, a .pdf file drawing of a house warning of some possible sources of asbestos in the home. The sources are not ranked according to actual risk of releasing hazardous levels of airborne asbestos fibers and the list is useful but incomplete.
 The US EPA provides a sample list of asbestos containing products epa.gov/earth1r6/6pd/asbestos/asbmatl.htm
 "Characterization of asbestos exposure among
automotive mechanics servicing and handling
asbestos-containing materials", Gary Scott Dotson, University of South Florida, 1 June 2006, web search 3/9/2012 original source: scholarcommons.usf.edu/cgi/viewcontent.cgi?article=3505&context=etd [copy on file as /hazmat/Automotive_Asbestos_Exposuret.pdf ].
 Thanks to Susan Kimball, Argus Pacific Corp., Puget Sound, WA, for pointing out that some products are permitted to contain more than 1% asbestos fibers by current standards provided that the fibers are encapsulated in an appropriate binder. Argus Pacific, in Seattle, WA 98119, 206.285.3373, is an industrial hygiene firm who also provide OSHA and DOSH regulated training in Washington State, providing classes in asbestos, lead, mold, hazardous waste, emergency response, and other occupational health, safety, and professional development topics. -- September 2008.
Work Practice for Window Removal and Window Putty Patching
With Less Than Or Equal To 1% Asbestos Window Putty and Caulking" University of Washington, 2002 http://www.washington.edu/admin/asbestos/1putty.html
 How do I Manage Asbestos in our House or Apartment Building?, Illinois Department of Environmental Conservation, provides this article at http://www.epa.state.il.us/small-business/asbestos-in-home/
 "Asbestos Awareness Training Outline", Michigan Department of Licensing and Regulatory Affairs, Michigan Occupational Safety & Health Administration, Construction Safety & Health Administration - asbestos program, Michigan Department of Licensing and Regulatory Affairs
Michigan Occupational Safety & Health Administration
Construction Safety and Health Division
7150 Harris Drive, P.O. Box 30671
Lansing, Michigan 48909-8171
Phone: 517.322.1320, Fax: 517.322.1713
E-mail: email@example.com, web search 3/9/12, original source www.michigan.gov/ [copy on file as /hazmat/Asbestos_awareness_training.pdf ]
 Damian Murphy, Marin OHS&E Consulting,Mairin OHS&E Consulting Pty Ltd
18-20 Kirk Street
Moe Vic 3825
P: 03 5127 2311
F: 03 5127 2399
E: firstname.lastname@example.org, personal correspondence to Daniel Friedman. 3/12/2013 Website: www.mairin.net.au
 Asbestos in buildings - employee notice, University of Washington dept. of Environmental Safety, http://www.ehs.washington.edu/ohsasbestos/index.shtm
 Window putty to be exempted from asbestos removal by State of Maine - http://list.uvm.edu/cgi-bin/wa?A2=SAFETY;wYpdKg;20010307113643-0500A
 EPA Region 6 identifies window putty as asbestos containing - http://www.epa.gov/earth1r6/6pd/asbestos/asbmatl.htm
June 1997 - Window Putty - OSHA case cites contractor for asbestos exposure during removal of window putty http://www.osha.gov/pls/oshaweb/owadisp.show_document?p_table=NEWS_RELEASES&p_id=1091
 Asbestos Identification and Testing References
Asbestos Identification, Walter C.McCrone, McCrone Research Institute, Chicago, IL.1987 ISBN 0-904962-11-3. Dr. McCrone literally "wrote the book" on asbestos identification procedures which formed
the basis for current work by asbestos identification laboratories.
Stanton, .F., et al., National Bureau of Standards Special Publication 506: 143-151
Pott, F., Staub-Reinhalf Luft 38, 486-490 (1978) cited by McCrone
 EM>Asbestos in Your Home U.S. EPA, Exposure Evaluation Division, Office of Toxic Substances, Office of Pesticides and Toxic Substances, U.S. Environmental Protection Agency, Washington,D.C. 20460
"Handling Asbestos-Containing roofing material - an update", Carl Good, NRCA Associate Executive Director, Professional Roofing, February 1992, p. 38-43
 EPA Guidance for Controlling Asbestos-Containing Materials in buildings, NIAST, National Institute on Abatement Sciences & Technology, [republishing EPA public documents] 1985 ed., Exposure Evaluation Division, Office of Toxic Substances, Office of Pesticides and Toxic Substances, U.S. Environmental Protection Agency, Washington,D.C. 20460
 Asbestos products and their history and use in various building materials such as asphalt and vinyl flooring includes discussion which draws on Asbestos, Its Industrial Applications, D.V. Rosato, engineering consultant, Newton, MA, Reinhold Publishing, 1959 Library of Congress Catalog Card No.: 59-12535 (out of print, text and images available at InspectAPedia.com).
Books & Articles on Building & Environmental Inspection, Testing, Diagnosis, & Repair
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